The efficacy of the Chagas' Disease Control Program was estimated in Minas Gerais State. Areas with different intervention times (10 and 5 years) and without intervention (control) were compared in order to verify a possible reduction in Trypanosoma cruzi infection incidence rates among those born after the Control Program. The Program efficacy was estimated comparing this study's infection rates with rates published by the Chagas' Disease Serological Survey, conducted between 1975-1980. The cross-sectional comparison for the 2-6-year age group showed a reduction of 94.7%, 63.2%, and 65.2% respectively, in areas where interventions had been carried for 10 years, 5 years, and in control areas. Cohort comparison, however indicated that reduction (52.6) occurred only in the area with 10 years of intervention. The data routinely collected by the Control Program were also analyzed and correlated with the incidence of T. cruzi infection. The results showed association between the Control Program and reduction in T. cruzi infection, measured by serological tests.